Setting and gameplay Harmonia is set in a
post-apocalyptic world sometime in the future. A rapid decline in human civilization began once the
population hit its peak of 10 billion, caused in part by pollution and war. During this time,
artificially intelligent, emotional
androids called Phiroids were developed to serve as partners for humans. Although Phiroids were originally powered by batteries for the first two generations, they were afterwards developed to be powered by eating food, making them nearly indistinguishable from humans. Artificial memories could also be implanted into the Phiroids, making them highly desirable, leading them to be produced in numbers that eventually rivaled the human population at a time when the
birth rate was already in decline. Eventually,
nuclear warfare and the resulting
nuclear fallout killed off most of humanity, culminating in a world covered in dark clouds and ash blocking out sunlight, land stripped of vegetation, and an ocean that could no longer support life. Some people were placed in
cryogenic facilities in an attempt to sleep long enough until the environment improved even a little bit.
Harmonia is a
visual novel in which the player assumes the role of Rei. The
gameplay is spent on reading the story's
narrative and
dialogue and follows a linear plot line; this is what Key refers to as a "kinetic novel".
Story Harmonia begins when the protagonist wakes up in a derelict facility
without any memories of who or where he is. Rei notices that his right hand is mechanical, and when he sees various Phiroids strewn about the facility, he assumes he is a Phiroid whose production went unfinished, as he also realizes that he does not have any emotions. To pay Shiona back for her kindness, Rei sets out to repair a broken
music box containing a song her brother had composed. Rei goes to the library to find a book to help in the repairs and meets the librarian, a little girl named who is constantly sad. Once the music box is repaired, Shiona is able to sing to the tune in the town plaza while Rei plays the music box. With the help of the townspeople, Rei also repairs a projector to play a film directed by the son of , the owner of the general store. Rei finds a heavily injured man and races to try to save his life, but the man shortly dies after he brings him to the church. The whole town shows up to show their respects at the funeral. Worried about Tipi's state of mind in dealing with the man's death, Rei repeatedly tries to go see Tipi, but Shiona keeps preventing him from going to see her. Rei eventually makes it to the library, but Shiona merely tells Tipi that her parents, who she has been waiting to return, are dead and that she will always be alone. Enraged at Shiona's behavior, Rei gets her to leave the library and Rei stays with Tipi overnight. Rei and Tipi wake up the next morning to find that the town is under attack. When Rei leaves to investigate, he finds humans have infiltrated the town and are killing the townspeople. Rei is nearly killed by them, but Shiona protects him from a gunshot, which leaves her unconscious, but alive. Rei takes Shiona back to the library where they regroup with Tipi before leaving through the sewer system to make it back to the church. A lone man comes to the church, and while Rei is fighting him, the man uses a grenade, but Shiona protects Rei from the blast. The aftermath of the blast makes Rei realize that he was human all along, and that everyone else in the town were Phiroids. After collecting some supplies, the three of them leave the town and make it to the facility where Rei originally woke up, which still has some electricity. Tipi gives Rei access to an electronic library on a
tablet shortly before her battery is no longer able to function. Rei and Shiona stay in the facility for a time until Shiona eventually succumbs to the gunshot wound which had damaged her internal components. Rei puts Shiona and Tipi in cryogenic pods before leaving with the music box in an attempt to find a world where humans and Phiroids can coexist. Sometime later, Shiona wakes up in a facility with her memories wiped, but she is told that there was a music box with her when she was found. The environment has recovered and human civilization is once again prosperous and highly technological. Shiona is taken back to the town where humans and Phiroids once again coexist. She is reunited with Tipi, who also had her memories wiped. Prompted by the tune playing from the music box, Shiona sings the song which is now known worldwide. ==Development and release==